This invention relates in general to the making of packs of interleaved (or interfolded) laminar articles.
A classic example of such an article comprises xe2x80x9cpaperxe2x80x9d handkerchiefs (in fact these are usually cellulose wadding or what is known as a non-woven fabric, depending upon whether the handkerchiefs are dry or premoistenedxe2x80x94the so-called xe2x80x9cwet wipesxe2x80x9d or, to use other current terms, xe2x80x9cmoist wipesxe2x80x9d or xe2x80x9cfacial tissuesxe2x80x9d) placed in corresponding box or envelope packages. The purpose of the interleaved arrangement of the individual articles is that the removal of one handkerchief from the pack automatically positions the next handkerchief in the pack so it can be pulled out.
The arrangements currently used to provide interleaved pack products are essentially based on two fundamental types.
A first arrangement is based on the concept of causing two strips or webs of sheet material to move forwards in positions facing each other. The two strips are subjected to a folding operation (and cutting, to separate the individual handkerchiefs) in positions facing each other so that the loops in the shapesxe2x80x94normally V or Z shapesxe2x80x94imparted to the handkerchiefs obtained from one or other of the two strips are at least partly interlinked. The result of this operation is the formation of a kind of chain of interleaved handkerchiefs of virtually indefinite length. The individual packs are then formed by merely introducing a break in the continuity of the chain. Documents U.S. Pat. No. 4,494,741 and U.S. Pat. No. 4,691,908, for example, provide examples of this arrangement.
The effectiveness of this arrangement is in fact impaired, particularly in view of the speed and complexity of the equipment required for implementing it, by the intrinsic complexity of the operation which causes the two strips to adopt a shape with interlinked loops. This operation is made even more complicated by the need to perform the cutting operation which results in separation of the individual handkerchiefs at the same time.
Another arrangement, which can be defined as being based on a principle of in-line operation, provides for forming a certain number of strips (or webs), for example by means of corresponding cutting operations performed simultaneously on a starting spool, in a number equal to that of the number of interleaved articles contained in the pack which it is intended to produce. The abovementioned strips are positioned into the desired conformation to ensure interleaving and are caused to converge towards a station where they are interleaved. As a result a composite strip or web comprising the interleaved starting strips is obtained. The composite strip obtained in this way is then cut to length at predetermined distances, and each length so obtained comprises a pack or block of interleaved laminar articles.
This arrangement overcomes the intrinsic limitations of the complexity and slowness of the arrangement described earlier, but pays for this advantage in terms of the general complexity of the system, in particular when the number of interleaved articles becomes large (e.g. 250 interleaved handkerchiefs, a format which is quite widely used in industry). There is therefore an intrinsic limit on flexibility given the fact that consumer requirements, in terms of the number of articles included in a single pack, are very variable, with contents ranging, for example, from a few units to more than two hundred units. Equipment operating on the basis of the arrangement described as the xe2x80x9cin-linexe2x80x9d arrangement can be converted to make packs containing a smaller number of articles once it has been configured to make packs containing a certain number of interleaved articles. It is not however possible to convert the equipment to make packs containing a larger number of interleaved articles. In any case reduction of the number of interleaved articles also requires fairly complex reconfiguration work (deactivating the sources of strip delivery and feed which are surplus to the number desired, etc.), which is hard to envisage in circumstances where conversion of the equipment""s operation is required for only a short period of time, for example for the manufacture of a small batch of products.
Yet another arrangement is described in European patent application 98830267.5, which is used as a model for the precharacterizing portion of claims 1 and 6. This arrangement provides for the making of a composite strip or web comprising a certain number of strips interleaved xe2x80x9cin-linexe2x80x9d from which two projecting branches or limbs project on opposite sides at terminal positions. The composite strip formed in this way is subjected to a transverse cutting operation performed in such a way as to give rise to breaks in continuity in an alternating sequence on the two projecting limbs so as to form easily breakable connecting bridges between adjacent blocks of interleaved products. The structure formed in this way is then subjected to folding in a general zigzag arrangement. In this way a final product comprising a pack of interleaved products is obtained and in fact comprises a plurality of blocks, each in themselves comprising a certain number of interleaved products, with adjacent blocks connected by the aforesaid bridges. The pack is inserted into a packaging such as e.g. an envelope or rigid-walled container and the products can then be removed by the consumer without the latter being aware of the existence of the aforesaid bridges, which break when the first product from each pair of products connected by such a bridge is removed from the pack. In practice the user is not aware of the fact that now and then (that is when passing from one block of products to the adjacent block within the pack) the product which is removed at the time is not interleaved with the next but connected to it by a bridge which breaks in the act of removing it.
The purpose of this invention is to provide an alternative arrangement which combines within it the positive features of all the arrangements described above, that is the simplicity and efficiency of the xe2x80x9cin-linexe2x80x9d arrangement, the flexibility of the arrangement based on the formation of a chain of interleaved products of indefinite length, and also the high flexibility and modular nature of the arrangement which provides for the formation of packs as complexes of blocks connected together by means of breakable bridges. All this however by giving rise, as a final result, to packs of products which are interleaved in a wholly uniform manner.
In accordance with this invention this object is accomplished by means of a process and equipment having the features claimed in the appended claims.